1. Field of the Invention
The present invention relates to a charged particle beam lithography apparatus and method, and an article manufacturing method.
2. Description of the Related Art
Lithography apparatuses that perform writing on a substrate by controlling deflection scanning and blanking of charged particle beams such as electron beams are known. The lithography apparatuses may be employed as one of pattern forming technologies that are an alternative to optical exposure systems to produce logic large scale integrated devices (LSI) or other highly-integrated devices having a line width of 0.1 μm or less. Among the lithography apparatuses, there is a multi beam lithography apparatus that writes a pattern in parallel with a plurality of electron beams (charged particle beams). The multi beam lithography apparatus has a number of advantages for practical applications, such as unnecessary use of a mask (original plate), which is one of factors responsible for increasing manufacturing costs, or a limited production of a wide variety of devices, because electron beams can be programmably controlled.
In order to independently control the tracks of a plurality of electron beams traveling toward a substrate, the multi beam lithography apparatus includes an electron optical system including a blanking deflector array and an aperture array (stopping aperture array). In the electron optical system, the blanking deflector array is disposed on the upstream side and the aperture array is disposed on the downstream side with respect to the direction of travel of electron beams. In particular, the blanking deflector array controls an OFF (blanking) state of writing by deflecting electron beams, and the aperture array is an electrical conductor having a plurality of apertures (openings) and physically performs shielding of the deflected electron beams. In the conventional multi beam lithography apparatus, if some portion, such as one where a beam defect occurs, of any one of the components relating to the writing ON/OFF state becomes uncontrollable after the start of operating the apparatus, a pattern cannot be written accurately. Hence, for example, it is contemplated that the blanking deflector array is replaced with a new one when a beam defect caused by the blanking deflector array occurs. However, multiple feed-power implementations need to be separated and a new failure may be induced in the course of replacement. Furthermore, it becomes difficult to replace the blanking deflector array from the viewpoint of cost and time with an increase in the number of beams for use.
In contrast, as an alternative that may provide a tentative counterpart for a beam defect (independent of replacement), Japanese Patent No. 4634076 discloses a charged particle beam exposure apparatus that compensates for electron beams in a shielded state at all times using electron beams that are controllable in a normal state. On the other hand, Japanese Patent No. 4313145 discloses a charged particle beam lithography apparatus that blocks electron beams in an unshielded state at all times by means of a shutter mechanism.
Here, according to the configuration of the charged particle beam exposure apparatus disclosed in Japanese Patent No. 4634076, with respect to electron beams in a shielded state at all times, it is possible to avoid in the stopping the apparatus, although such a configuration may have an adverse effect on throughput. On the other hand, the configuration of the charged particle beam exposure apparatus disclosed in Japanese Patent No. 4034070, with respect electron beams in an unshielded state at all times is not preferred, because the configuration of the apparatus becomes complicated due to the addition of a shutter mechanism, so that normal electron beams located around electron beams in an unshielded state at all time are also blocked. Therefore, as high density multi-beam formation progresses, accompanying the recent tendency of refining a line width, countermeasures against electron beams in an unshielded state at all times (incapable of blanking) are particularly required.